What product? My lights are so dirty you can't see the bulbs. Figure it's only a matter of time til they fail annual PA inspection.
I just drove 3000 miles from L.A. to Salt Lake City, to Philadelphia. Car held-up just fine though fast driving only gave me 58mpg.
Product isn't that important to me, just used some swirl remover stuff, followed by Aeroshell Plexicoat and then a hand application of Rejex; all stuff I already had laying around the garage.
To my mind the real important item is a Makita 9227c polisher. It isn't cheap, but it's endlessly useful in keeping your cars shiny.
I have a couple of Buick Reattas which have polycarbonate full-width clear outer lenses on the taillight assemblies that oxidize something awful if you don't keep them polished and given that it's such a prominent styling element of the car it's hard to ignore as they change from clear and glossy to opaque and a beige-ish matte. I did my Reatta taillights by hand for over a dozen years, ignoring the advice a knowledgeable friend who lives out here in Arizona. A couple of years ago I was visiting AZ and he showed me how it made quick work of restoring the appearance of a trashed Reatta taillight and I was sold, bought one as soon as I got back home to NY. Wish I had listened to him sooner.
I was mainly cleaning up the headlights for cosmetic reasons, I bought the Insight out here in AZ so I wanted it looking appropriately spiffy for my friends and family back east who haven't previously seen it. I really didn't realize the amount of output I was losing until I noticed how much better I could see while driving at night.
One of those headlight restoration kits that attach to a drill would probably work, though you should try to put on a UV protectant afterwards to help forestall the inevitable re-haze for as long as possible.
I did a trip from Phoenix to San Diego and back in my Insight recently and managed 67MPG. I figure taking the Honda and getting say 60-ish MPG vs the 20-25 that all of the rest of the fleet seems to get makes it a no-brainer, besides I don't want to accumulate miles on the other (older and low mileage) cars or potentially expose them to road salt. Dunno how I'll feel about my decision 2000 miles into the trip though. Hopefully my back will be able to take it.
Car was serviced today by the Honda dealer. Fumoto valve is installed, though I was surprised that they removed the externally-mounted tear-drop shaped rubber thingy from the engine block. It ain't leaking so I guess it's fine?
They bring the car out front for me to drive away and the check engine light was on. So, back I take the car back into service department where four guys stood around scratching their heads, checked and reset the codes and the "service advisor" told me it was an oxygen sensor code for "no signal" and it could be "bad gas". (sigh) Well the SES light was off at that point so there's wasn't anything to be gained by arguing with him.
Oh, and they thoughtfully let the air out of my tires so I had 30PSI all 'round.

I've put 'em back to 50PSI.